Maija Mustaniemi-Laakso, Hans-Otto Sano, editors
Routledge, Taylor & Francis Group, 2017
Buku Teks
Olawuyi, Damilola S, author
Cambridge University Press, 2016
eBooks
Cambridge University Press, 2019
eBooks
edited by Sir Francis Vallat
Europa Publications, 1970
Buku Teks
UNDP
Oxford : UNDP, 2000,
Buku Referensi